Sen. John McCain (R-Ariz.) today said the Obama administration's policy toward the civil war in Syria was "a shameful chapter in American history."

McCain, the ranking member on the Senate Armed Services Committee, made the comments after exiting a committee briefing with Defense Secretary Leon Panetta about Syria that also addressed the broader unrest in the Middle East.

"The president refuses to even speak up. When was the last time the president of the United States spoke up for the over 20,000 people - men, women and children - that have been massacred by Bashir al-Assad," McCain said. "Obviously, we are not providing assistance to them, according to published reports."

Sen. Susan Collins (R-Maine) said about 27,000 Syrians have now been killed at the hands of the forces associated with Assad, Syria's president.

"And to me, the question is at what point is that considered a mass atrocity that demands us to start providing lethal aid to the opponents of the regime?" Collins asked.

She was more circumspect about the challenges faced by the White House and the Pentagon, however.

"I readily admit that these issues are extremely complicated," she said. "There is a legitimate concern of the administration about whether, if we provided weapons, they would fall eventually into the wrong hands. So, this is extremely difficult, but I am very concerned that the administration does not seem to have a real plan to deal with Syria."

The Senators who spoke to the media about Syria have typically favored a more hawkish foreign policy in defense of U.S. interests, led by McCain.

Sen. Joe Lieberman (I-Conn.) has traveled to the Middle East with McCain many times but stopped short of calling out President Barack Obama for American weakness on foreign policy, as McCain seemed to.

"Last week, Sen. McCain and I were in a couple of Arab countries in the Middle East, and they were really calling out to us for more American leadership. I don't personally believe that . it's because of American policy that any of these things are happening, but I do believe that there's more that we can do and that we have a national interest in doing in trying to bring more stability to the Middle East."

Lieberman added, however, that he agreed with McCain on the need to do more in Syria.

Libya Also Discussed

Senators spoke with Panetta about the response to the situation in Libya. Four Americans were killed in an attack Tuesday on the U.S. consulate in Benghazi, including Ambassador Chris Stevens.

Senators said it has become clearer the attack was coordinated, although they would not say anything specific about any connection to the broader protests that came after an anti-Muslim video was released.

"I think it was a planned, premeditated attack," Senate Armed Services Chairman Carl Levin (D-Mich.) said. He added he did not know the specific group responsible for the assault on the complex.

McCain expressed a similar view.

"People don't go to demonstrate and carry RPGs and automatic weapons," he said, adding that the facts suggest "this was not a 'mob' action [or] a group of protesters."

"Whenever something like this happens, there is obviously ... a failure. Whether that failure was of great significance or nonsignificance or it was one of those things that probably couldn't have been prevented," McCain said. "I'm not ready to indict our intelligence community until we get more facts"

However, Collins said she had serious concerns about the security at the consulate in Benghazi, particularly in the aftermath of other incidents over the summer involving the Americans and the British.

"My overwhelming concern is that I don't understand why the consulate was not better guarded, given the attacks that were aimed at the British ambassador in June, the bomb that exploded outside the consulate - also in June," Collins said. "The threat environment was such that to leave the defense to Libyan nationals just doesn't make sense to me."

In the immediate aftermath of the attack on the consulate, Obama ordered additional resources to provide security to diplomatic facilities in the region.